"Clunk" / "Clank" sound at initial start up?

[Sig556]

Every time I think I'm about ready to take the boat out, I run into another issue.  You can look back at all my posts to see what's happened in the past and how close I get to hooking the boat up to go to the lake.  In a couple of sentences, here's the back story.  Boat purchased two years ago.  Been on the water 2x and broke down each time.  Last time was a major overheat issue that resulted in water in the engine/oil.  pulled the heads, resurfaced & check out; new gaskets and put it all back together.  

The last thing I thought I had to deal with was the carb issue I asked about a couple weeks ago that I think is now sorted out.  I should be happy because that was supposed to get me on the water.

My New ISSUE: the last 5-6 times I've started the engine, there is "clank" or "clunk" sound that seems to come from the front of the engine.  I bump the ignition and the noise happens.  Turn the key to off and try to start again, sometime the sound is there, other time no.  If I bump it and the noise happens and stop, then start it, the sound may or may not reappear.  If it does, it's for only a the briefest of moments, then it often sounds like a "normal" start up.  When the engine runs, it sound fine and does not seem to have any odd noise, etc.  I can stop and restart with our any noise - seems to be on a cold start. 

I thought it might be low battery with not enough juice, so I pulled them and recharged/rehabbed them.  Had them tested at a couple auto parts stores and they said they tested good.  That didn't seem to address the issue, noise is still there.  

I'm baffled because the noise was not there after I put the engine back together was playing with the RPM/Carb issue.  I must have started the boat 10-15 times w/o incident; then it begins to happen. 

Not sure if there is a bad starter and it sounds like the noise is coming from the front of the engine?  Might I have messed up the transmission engage/disengage cable and the prop is engaged when I try to start?   Did something come loose internally, but I can't figure out what (need to pull the valve covers & retighten the lifters/rocker arms?).  I've checked the oil and I am not seeing any water in the oil. 

I've run the engine since it's been put back together probably a total of 20-25 minutes. Always on water and temp, from a temp gun, no hotter than about 165-170 in on the exhaust manifold.

Like always, I'm open to suggestions and appreciate any feed back. 

[Sig556]

Follow up and resolution.
 

I searched all over the internet trying to figure out what my issue was.  As mentioned, sitting in the driver seat tryin to start the engine, the sound appear to originate at the front of the engine (behind water pump and the crank/cam gears) and it sounded like metal fan blades "clanking" together for an instance.  Was discussing it with my buddy and I recorded the sound 2-3 times under different scenario's - sitting in the cockpit.  Upon reviewing the recording, which muffled and somewhat isolated the sound, i heard distinct starter motor issues.  Replaced starter motor and all's good.

Now I can get back to dialing in my carb, finding a water temp gauge that will fit, hooking my water inlet back up to the thru-hull intake.  Then an on the water test.